1. Field of the Invention
The present invention relates to a liquid crystal display device.
2. Description of the Related Art
As a display device of an information communication terminal such as a computer and a television receiver, liquid crystal display devices are extensively used. The liquid crystal display device changes an electric field to change an orientation of a liquid crystal composition confined between two substrates, and controls the transmission degree of light passing through the two substrates and the liquid crystal composition to display an image. In order to change the electric field, a voltage corresponding to a gradation value of each pixel is applied to a pixel electrode through a pixel transistor of each pixel.
If the liquid crystal composition is continuously applied with a voltage of the same polarity for a long time, the liquid crystal composition chemically changes, and is deteriorated. For that reason, in the liquid crystal display device, it is general to display the image by so-called “inversion drive” which conducts driving while inverting polarities between pixel electrodes and a counter electrode opposed to the pixel electrodes.
The inversion drive includes frame inversion drive in which the respective pixels in a certain frame have the same polarity, line inversion drive having the same polarity in a horizontal direction, column inversion drive having the same polarity in a vertical direction, dot inversion drive in which pixels of the same polarity are shaped in a checkered pattern, and pixel inversion drive in which pixels of the same polarity are shaped in a checkered pattern on a pixel basis (one pixel by RGB).
In general, it is difficult to completely eliminate a luminance difference between a case in which a positive electrode is applied and a case in which a negative electrode is applied, in the inversion drive, and there is known that flicker appears in the frame inversion drive, and stripes caused by eye movement appear in the line inversion and the column inversion drive. Also, since the polarity of a drain signal is the same in one frame in the frame inversion drive and the column inversion drive, capacitive and leaky crosstalk is likely to occur, and the dot inversion or pixel inversion drive is desirable from the viewpoint of image quality.
Japanese Patent No. 4877363 discloses the inversion drive of the liquid crystal display device having sub-pixels of four colors.